The present innovation pertains to determining nutritional caloric intake, and in particular to an approach that indirectly determines caloric intake usable outside of a clinical setting.
Significant development and investment has been made in accurately determining the calories in each kind of food. Examples of such technology include reaction calorimeters (e.g., bomb calorimeter), constant-pressure calorimeter, differential scanning calorimeter, isothermal titration calorimeter, X-ray microcalorimeter, heat-loss calorimeter, and high-energy particle calorimeter. References thus abound for providing nutritional content of food both in bulk and packaged for sale.
Leveraging such knowledge, many who seek to lose weight have had to maintain written journals of all foods eaten in order to gain awareness of their caloric intake. Thereby, limits on the total calorie and the types of calorie (e.g., fat, starch, protein, etc.) can be imposed. Although some have the discipline to objectively and consistently keep such journals, most find this technique too difficult.
A modest improvement has been realized with portable devices (e.g., personal digital assistants, digital notepads. etc.) that can record the journal information. Even with some assistance for calculating and tracking food intake, such devices still rely upon the user to remember to input the data and to be accurate about the quantities consumes. It has even been further proposed to have a portable photographic system that visually records images of the food consumed in order to keep better records. However, each of these approaches and devices suffer when the user is a social setting that is not conducive to recording such information (e.g., at a party, midnight snacking, etc.)
Even in clinical settings (e.g., hospitals, premier sports training programs, etc.) that have greater accountability over what food is served, often indirect calorimetry techniques are used. Presumably, diet journals would be nearly as cumbersome even in such environments. Typically, indirect calorimeters measure respiration flow rate and the fraction of the oxygen that is converted into carbon dioxide. These can be used to determine resting metabolic rate (RMR) or even metabolic efficiency during certain carefully orchestrated exercises (e.g., treadmill). Generally, such clinical respiration-based indirect calorimeters are not practical or desirable for everyday use.